Air-pump.



C. W. MoGARY.

Am PUMP.

l APPLICATION FILED JAN. 28, 1910.

" Patented Aug. 15,1911.

3 SHEETS-SHBET 1.

' I 0; W. M'OGARY.

Patented A 171g. 15, 1911. 3 SHEETS-SHEET 2.

j 5&5 '.Zfaz/vwavf: man@ y ya i l v fwy.

C. W. MGGARY.

AIR PUMP.

APPLICATION IILED JAN. 28, 1910.

1,000,615. v 'PatenteaAugfmlgll'f s SHEETS-SHEET 3.

A,UNITED STATES Pnr1ri-sfi- OFFICE.

CHARLES W.

MUGARY, F EVRETT, MASSACHUSETTS, wASSlKarNOIR, 0F ONE-HALF p HERBERTLIHILDRETI-I, OF BOSTON, MSSACHUSETTS AIR-PUMP.

` Specification of Letters Patent.

. Patented Aug. 15,1911.

Application inea January l2e, 1910. serial no. 540,490.-

.the following is a specification, reference being had therein to theaccompanying drawings. Y O

My invention relates to air pumps or blowersjof the class in whichtwo-rotating members or rotors inclosed in a casing cooperate to drawair in through a suction opening .and expel it under an increasedpressure through a discharge opening. As heretofore constructed, sofaras is known to me, blowjer's of this classhave been'able to compresslthe air to a manimum pressure of only ei ht orten pounds tothe squareinch, after whlch an increase in the speed of the rotors does notincrease .the lamount of compression to any considerable extent. As a.result of this fact, it has been necessary to usereciprocat-Y ing airpumps where 4the vpressure desired f was greater than the amount stated.The

failureof rotary blowers as heretofore constructed to produce a pressureabove ei ht or ten pounds is believed to havebeen 'ue to the fact thatthe pockets ofthe female rotor.

operate to carry out of the chamber in whichv the compressed air iscontained a certain amount of the air under pressure, and the proportionwhich the amount of alr carried outb'y the female rotor bears to theamount carried in by the malerotor increases as the pressure inthedischarge outlet increases,

` so that'at a certain speed as mu'ch air. is car,-

i attempts have 'been comparatively ineifectual for the pur ose'.intended, and have ried` out by the female rotor as carried in by themalefrotor. Some attem ts have been made tOeauSethecompressed air in thepockets of the female rotor to' be discharged into the pockets oftheniale rotor but such great-1y lessened th strength-of the rotatingparts which must be very great to venable the rotors to run at the highspeedsA required.` v l My improvedrotary air pump 1S providedwith-rotors ofnovel construction which practically eliminate allpockeltnig of compressed' air anditis found in practice that an air pumpembodying my construction will delllver compressedair at a pressure verymuch in excess of any which it has heretoforebeen possible to obtainwithout the use of a reciprocating air pump, so far asis known tome.

The invention will be fully understood from the following descriptiontaken in connection with` the accompanying drawings, and the nielfeatures are pointed out and clearly defined in the claims at the closeof the specification. f

In the drawings-Fi ure 1 is a vertical section of va device embo ying myinvention. Figs. 2 to 5 inclusive are sections on line .2-2, Fig'. 1,showing the rotors in various successivepositions.- Fig. 6 also shows amodification intended to give an uneven or jerky suction. Figs. 7 and 8are details showing the construction of the leakage portby means ofwhich the' machine is kept from pounding when running at high speed:Fig. 9 is avertical section through the casing of invention, the rotors.being shown in elevashown'at 1l; the female rotor at 12; and the sovmale rotor at 13.l The said casing is con- '1 `struc'ted in anyconvenient mannerand fits the peripheries and ends of the rotors /veryclosely so as to prevent' the escape of air between the proximatesurfaces ofthe casing and rotor.l v Inpractice I nd it convenient togrind-in the/rotors by the use of pow-` deredemery or some othersuitable abrading substance. In the'form shown in the drawings, thefemale f rotor is. supportedmn an axle ,14 and'themale rotor on-'an axle15,

said members being rotated atequal speeds bypmeans of gears .16 and 17,respectively, power beingv applied to .the pulley 18.

While I have shown the two rotors as .being driven with equal speeds, itwill be obvious that they ymaybe driven at. different vspeeds offrotation, 1f desired for 'any reason, so long` perlpheral'speeds'.

' The air.` to be'compressed through ,pipe 19 on the suction side of theSthey are designed to `have the same,

is drawn in 7s "y a modified form -of air pump embodying my blower'anddischarged'through pi e 2O on the'discharge side. .The casing onv 0ththe suction and discharge sides is made to foll flow the circumferenceof the rotors as far fas possible, as will be plainly seen from Figs.

- 2 to 5 inclusive. The casing is shown as cnd` air through thedischarge pipe.

ing on -the discharge side in a groove 28, which assists in the escapevof the compressed The male rotor is constructed with a plurality oflongitudinal projections or blades '21, 22y and 23 which are inconstruct-ion practicall-y gear teeth. In practice I find three to be aconvenient number of these blades.

follows what may be termedl the addendum circle, so that the peripheryof the rotdr iits 4closely to the interior 0f the casing.

The pockets in the.female rotor are of a depth equal to the lbngth ofthe blades so that the ends of the blades contact with the bottoms ofthe pockets and the peripheral portion of the female rotor between twoadjacent pockets contacts with thefperipheral portion of the male 'rotorlying between the roots of two adjacent blades. From this it will beseen that there is no end clearance and that the addendum circle ofthefemale rotor contracts with the root circle of the male rotor. Theblades or teeth and thecorresponding walls of the pockets are soconstructed as to remain in contact witheach other constantly either onthe walls cron the bottomof the pocket from the time the blade entersthe pocket until it leaves it, so that there is the least possibleleakage between 'the rotors.

By .this'means the compressed air containedv l 'j in the pocket which isopen to the discharge side o the blower is forced back into thedischarge side of the blower by the bladef which is entering the pocket.As the two rotors are always in contact with each other and the point ofcontact progresses alon the- `root circle of the male rotor up the si cof,

rthe blade, along the point ofthe blade, down the other side of theAblade, and again along the root circle toward the next blade, it will beseen that the compressed air is constantly forced backward'froln thepoint of contact and no escape,- except to the discharge side,ispermltted. I nd in actual .zpractice that the .contact betweenthe-male and female members `may be made'so perfect -thatno'escapepfair` into.. the suction side of the air pump iS. tobe observed. I haveaccomplished this by making the blade to corres ond in shape withinvolute gear teeth slighty -modiied at the point. and base to prolong.the time of contact untilthe end of the tooth strikes the bottom ofthepocket.

'It will be understood, of course, that the pockets of the female rotoralso carry small quantities of air to the discharge side of the airpump, but the pockets between the bladesof the' male rotor carry in byfar the greater. proportion of the air.

A It will be seen that when the position shown in Fig. 2, the airbetween the blades 22 and' 23 is at substantially at- Vmosphericpres'sure,"and that the air in the space between blades 23 and 21 is atatmospheric pressure, except for any leakage-- the parts are in whichmay have occurred from` the discharge 'side ofthe air pump. As soon as.the blade 21 passes-the extreme edge 27 of the casing, the air underpressure from the discharge side rushes into the said space and raisesthe pressure untjfl/ it is equal to the pressure on the discharge side.Thereafter the forward movement of the blade 23 compresses all the airin said space and on the discharge side of the air pump until the blade23 itself passes out of contact with the edge 27 of the casing. If theblades are fitted closely enough to give a maximum efliciency, it isfound 'that pounding results due to the sud den inrush of air 'underpressure .into the space between the two adjacent blades. T o

prevent this pounding, I form a small leakage portV 28, .see Figs. 7 and8, so that the compressed air from the discharge side of the air pumpbegins to iow slowly into the and. compact so that the parts may be runata very high speed without danger of in jury from centrifugal force,but the constructiondoes not prevent the parts being made hollow ifdesired.

In Fig. 9 I haveshown -two rotors pro- 'vided with blades and pocketswhich are substantially spiral gearteeth. While such construction issomewhat more expensive to produce, it is believed that itwould tend toVincrease materially'the quiet operation of .the blower as the pressurein the discharge side. ofthe blower is raisedless suddenly than in theforms shown in the other vfigures.

In' Fig.'6 there is shown a slight modification of'fmy rotary air pumpadapted especially vfor use Uin connection withgasolene carbureters inwhich it is desirable t0 suck air through a carbureter', thereby causingit to 'forma mixture with gasglene introduced in the formvof a jet andto compress.

saidmixture" for-use in the cylinders of' an internal combustion .engineUnder these conditions it is desirable that the suction on Ithecarlmreter be irregular at slow speeds as itis found in practice that asteady current of air moving withless than a certain Velocity will notbreak up the` jet of gasolene and form the desired mixture. It 1s,therefore, desirable that the suction be irregular or jerky, as therebythe formation. of the mixture at slow speedsis greatly improved. Toaccomplish this result, I place the suction opening 35 part way down thecasing of the male rotor and make lsuch suction openin in the form of anarrow port which is close at times by the end of the blade of the malerotor. W'hen the parts are in the position shown in Fig. 6, thef'urthermovement of the blade 2l of the male rotor forns a partial vacuum in thespace back of said blade,

l said vacuum becoming more perfect as the saidlblade approaches theport`35. /As soon vas the blade passes the port, the gasolene miXturcrushes in suddenly to filll the Vacuum.

.at slow speeds.I 'At high speeds, littleor no difference will be seenin the action over. that of theform shown in the other figures.

lVhat I claim is:

l. In a rotary :air pump, the combination 0f a female rotor and 'a malerotor, said female rotor being provided with adseries of peripheral'pockets and said male-rpatffi' being provided`with a correspondingseries of blades equal in numberwith the pockets of the female rotor,the distances between the pockets of the female rotorbeing greaterthanthe width ofthe pockets and the distanc'cs between they teeth of themale rotor casing having` two intersecting cylindri-v being greater thanthe width of the teeth, the spaces between the pockets ofthe femalerotor being solid and the spaces .between the teeth of the male rotorbeing hollow,l the radius of sweep of4 the teeth of the male rotor beingthe same as the radi'usfof sweep of the body of the female rotor, saidtwo rotors having their axes of rotation parallel with each other andspaced apart so that the teeth of theI male ro o will :mesh with andbottom in the pockets of the female rotor during the' rotation andtheperipheries of the bodies' of thetwo rotors will have a sliding Contactwith each other'and cal chambersparallel with each other and openinginto each other at their intersecing portions, the interior diameter ofIn this form, a little clearance is made between the female/rotor andthe cas-v oth the diameter of the circle swept by said rotors wherebythere is a close sliding tit of the rotors wit-hin said cylindricalchambers and'v permitting rotation of the rotors,

2. In a rotary fair'pump, the combination of a-female rotor and a malerotor, said fc- Inale rotor being provided .with a series of `peripheralpockets and said male rotor being provided with La corresponding seriesof blades equal in number with the pockets of the female rotor, thedistances between the pockets of the female rotor being greater thanlthefwidth of t-he pockets and the distances betweenthe -teeth of themal'erotor being greater than the-width lof the teeth, the spacesbetween the pockets of the female rotor being solid and the spacesbetween the teeth of the male rotor being hollow, the radius of sweep ofthe teeth of t-he male rotor being the same as the radiusot' sweep oflthe body of the -female rotor, said two rotors having their axes ofrot/ation parallel with each other and spaced'apart so that the teeth ofthemale rotor-will mesh with and bottom in t-hepockets of theA femalerotor during the rotation 'andy the peripheries of t-he bodies of the.Vtwo rotors will have a sliding contact with each other and a casinghaving two intersecting cylindrical chambers parallel wit-li each otherand opening into each other at their intersecting portions, the interiordiameter of both chambers being equal to eadh other and to the diameterof the circle swept by said rotors whereby there is-a 'close sliding fitof'the rotors within said cylindrical chambers and `cliambersloeingequal to each other-'fand to v permitting rotation of the rotors, saidcase ing having an inlet opening and a discharge -open1ng, s aidrotors-being at all times in lcontact with each other at some pointbetween the inlet and the discharge openings.

3. In arotary air pump, the combination of a femal'erotor and a malerotor, said female rotor being provided with a series of peripheralpockets and said male rotor being --provided with a corresponding seriesof blades equal in number with the pockets of the female rotor, t-hedistances between the pockets of t-he female rotor being greater thanthe *width of the pockets and the distances between the' teeth of themale rotor being greater than the width of the teeth, y

the spaces between the pockets of the female rotor being' solid and thespaces between the teeth of the male rotor being hollow, the radius ofsweep fof the teeth of the male rotor beingthe lsame as the radiusofsweep ofthe body of the female rotor, said twlo' rotorshavingtheiraxes of rotation parallel with each other and spaced apart so thatthe teeth of the male rotorwill mesh with the pockets of thefemalrotorduring the rotation andthe peripheries of the bodies of thetwo rotors will Contact with each iso - cylindrical cham ers parallelwith each rotors.

other and a, casin having two intersecting chambers and permittingrotation of the 10 other and opening into. each other attheir Intestimony whereof I aiixx rny sgnaitersecting port-ions, the interiordiameter ture, in presence of'two Witnesses.

=' of both. chambers being equalto each other CHARLES W. MCGARY. and tothe diameter of the circle swept by Witnesses: said rotors whereby thereis' a close shdin GEORGE P. DIKE,

lit of the rotors within said cylindrica ALICE H. MORRISON.

